The measurement of the electrical constants of soil by a lecher-wire method at a wave-length of 1.5 M

Abstract

The paper describes an investigation carried out by means of a laboratory method of measuring the electrical properties of soil with alternating current of a frequency corresponding to a wave-length of 1.5 m. A parallel Lecher-wire system was set up and coupled to a source of oscillations of the desired frequency. The length of the stationary waves set up on the wires in air was measured and compared with the corresponding wave-length when the wires were immersed in the sample of soil under examination. The ratio of these wave-lengths gives directly a quantity involving both the conductivity and the dielectric constant of the soil. This quantity was measured for typical samples of Teddington soil having a wide range of moisture contents, and from the results deductions are made as to the values of the conductivity and dielectric constant of soil for various moisture-content conditions. Thus for conditions of normal moisture content the dielectric constant is found to have a value of 10 or 12, while the conductivity lies within the range 10 to 28 × 108 e.s.u. These values are in good agreement with those obtained by the use of a field method on the same site and at the same wave-length, and their accuracy is adequate for most purposes in connexion with radio communication.